(E)-1-(2,4-Dinitro­phen­yl)-2-pentyl­idenehydrazine

The title compound, C(11)H(14)N(4)O(4), is essentially planar with an r.m.s. deviation for the 19 non-H atoms of 0.152 Å. The conformation about the C=N bond is E, and the mol­ecule has a U-shape as the butyl group folds over towards the aromatic system. An intra­molecular C—H⋯N inter­action occurs. The crystal packing is dominated by N—H⋯O hydrogen bonding and C—H⋯O contacts, leading to twisted zigzag supra­molecular chains along the c direction. The crystal packing brings two nitro O atoms into an unusually close proximity of 2.686 (4) Å. While the nature of this inter­action is not obvious, there are several precendents for such short nitro–nitro O⋯O contacts of less than 2.70 Å in the crystallographic literature.